Watertight watch cases for wrist watches

ABSTRACT

In a waterproof watch case, a plastic, outer case-body encloses a ring-shaped inner case-body. The plastic case-body acts as a shock absorber and can be colored to enhance the appearance of the watch.

United States Patent Fujimori [54] WATERTIGHT WATCH CASES FOR WRISTWATCHES [72] Inventor: Xqshiaki Fujimori,Suwa, J apan [73] Assignee:Kabushiki Kaisha Svwai Suikasha,

[22] Filed: March 12, 1970 [211 App]. N0.: 18,990

[52] US. Cl. ..58/90 R, 58/91 [51] Int. Cl. ..G04b 37/08 [58] Field ofSearch ..58/88 R, 88 G, 88 W, 90 R,

[56] References Cited UNITED STATES PATENTS 2,765,614 10/1956 Steirnann..58/90 R Aug. 29, 1972 2,586,086 2/1952 Pretre ..5 8/88 G FOREIGNPATENTS OR APPLICATIONS 219,449 2/ 1942 Switzerland ..58/90 R 310,87211/1955 Switzerland 58/88 W Primary Examiner-Richard B. WilkinsonAssistant Examiner-George H. Miller, Jr. AttorneyBlum, Moscovitz,Friedman & Kaplan [57] ABSTRACT In a waterproof watch case, a plastic,outer case-body encloses a ring-shaped inner case-body. The plasticcase-body acts as a shock absorber and can be colored to enhance theappearance of the watch.

3 Claims, 2 Drawing Figures WATERTIGI-IT WATCH CASES FOR WRIS WATCHESBACKGROUND OF THE INVENTION In order to provide the needed strength forassuring water-tightness watch cases are generally made of relativelystrong materials such as stainless steel or brass. Colors are restrictedto those of silver and gold. This limited range of materials does notprovide as wide a range of colors as could be desired,particularly inview of the fact that dials can be made in a wide variety of colors.

Furthermore, in the interest of minimizing the weight of the wristwatch,it is desirable to use relatively thin case materials. However, suchcase materials are subject to defacement by relatively minor impact.

SUMMARY OF THE INVENTION The metal, inner case-body of awatch is made inring shape, and a plastic outer case-body encloses the metal, innercase-body. The plastic outer case-body engages the metal, innercase-body and is held thereto by a metal bezel, made of metal and fixedinto the inner case-body at the upper portion thereof. The plastic outercase-body, in general, is colored in order to enhance the appearance ofthe watch.

Accordingly, an object-of the present invention isto provide a watchcase which is lighter in weight than conventional watch cases.

Another object of the inventionis toprovide a watch case which is moreresistant to defacement by impact or shock.

A further object of the invention is to provide a watch case of enhancedappearance.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross sectional view of aconventional watch case for a wrist watch;

FIG. 2 is a cross sectional view of one embodiment of a watch case for awrist watch according to'the invention.

DETAILED DESCRIPTION OF THE INVENTION The present invention relates towatertight watch cases made of plastic materials for wrist watches.Conventional watertight watch cases usually comprise a case body 1provided with a band attaching lug 4, a bezel 2 engaging the upperprojected portion of case body 1 with a certain interference, crystal 3,a case back 5 and a packing 6. This watch is constructed so that crystal3 is compressed into the case body 1 with a certain interference, theouter peripheral wall of crystal 3 and the inner peripheral wall of thecase body 1 are fitted rigidly and further packing 6 is deformed byscrewing the case back 5 into the case body 1 in order to ensure thewatch being watertight.

With the above-mentioned construction, mechanical strength is requiredin the interference portion or a screwing portion of a watch case. Thusmetal'materials such as stainless steel or brass have been applied to awatch case.

However, these materials are practically restricted in coloring, namelyrestricted to silver and gold. Thus watches of various colors could'notbe obtained.

' user, therefore, feels uncomfortable when wearing it on his wrist.Also, in the production of such watch cases, made of metals, thedifficult work, such as cutting or pressing are required in addition toextensive time and thereby making the cost run very high. Since theconventional watch cases are made mostly of metals, rust is apt togenerate thereon when subjected to moisture or water, thus causing thelife of the case to be very short.

One the other hand, the purpose of the present invention is to eliminatethe above-mentioned defects and to provide a watertight watch with acase made of plastic material. Plastic has the following merits, i.e.,high workability, optional coloring and lightness in weight, while ithas the following disadvantages, i.e. poor mechanical strength. For thisreason, it has not been applied to a watertight watch which requires themechanical strength but sometimes applied to only non-watertight watcheswith relatively low cost.

The present invention makes it possible to apply plastic material to awatertight watch by employing the construction as shown in FIG. 2.

Referring now to the embodiment shown in FIG. 2, 7 is an outer case bodymade of plastic material. 8 is a ring-shaped inner case body made of ametal, and engaged with crystal 10 and case back 11 made of a metal. 9is a bezel made of a metal and fixed into the inner case body 8 at theupper portion of the outer case body 7 with a certain interference. 12is a packing and 13 is a flat-surface formed in the periphery of theinner casebody 8 to receive the outer case body 7. Further theembodiment has such construction that the outer case body 7 is fitted tothe periphery of the inner case body 8 from the upper side andinterposed between the flat surface 13 of the inner case body 8 and thebottom of the bezel 9 fixed to the upper portion of the inner case body8. The outer case body 7 is secured to the inner case body 8.

Concerning watertightness of the case above-mentioned, it is constructedso as to ensure it being watertight in the same manner as in thecommonly used watch cases. The crystal 10 is compressed into the innercase body 8 with certain interferences both in the inner periphery ofthe inner case body 8 and in the outer periphery of the crystal 10 so asto fit rigidly with each other. The case back 11 is then screwed intothe inner case body 8 and the packing 12 is deformed in order to ensureit being water tight.

In this case the connection between the outer case body 7 and the innercase body 8 may be other means, for example, by screws, engaging means,deformation by heat or adhesives.

As is apparent from the above description, a watch case according to thepresent invention is divided into two parts in its case-body portion,i.e., an inner case body portion requiring mechanical strength and anouter case body-portion (visible portion from the outside)-requiringmedium mechanical strength, the inner case body portion being made of ametal and the outer case body portion being made of plastic material.Con- 'cer'ning watertightness, this watch gives the same performance asthe conventional metal watch. Moreover, as the outer case body portionis made of plastic material, the coloring can be optionally selected andvarious colors of watches can be obtained.

Besides, in this case, the coloring is not applied to the foundation ofthe case as in plating or painting, but can be applied to the plasticitself, and the initial color can be maintained for a long time withoutpeeling. Further, the color of the case can be matched with that of theband or dial, or patterns can be suited to each other, and furthersuitable color arrangement can be applied between the parts. The outercase body made of plastic material is easily formed by the injectionmolding. As the inner case body, made of a metal, is in a form of aring, the pressing from a sheet material as usual is not required. Thisallows the mass-scaled production and the reduction in the cost ofproduction. Thus watches with low costs can be supplied to the market.

Since the outer case body is made of plastic material, it is very lightin weight, and when wearing it on the wrist, one does not feeluncomfortable.

The conventional watch case made of a metal has been restricted in formin machining and only the case with relatively simple shape could berealized. Now, however, the outer case body portion can be made by theinjection molding. This makes it possible to produce the case of thecomplicated shape, and many watches in great variety of designs can beobtained.

By the injection molding above mentioned, some means, i.e., projectedportion, etc., can be easily formed in the inner wall of the outer casebody in order to prevent the rotation force caused between the outercase body and the inner case body by turning the screws of the caseback. Furthermore, as the outer case body portion is made of plasticmaterial which has an elasticity, if the watch should be carelesslydropped, it

can absorb a shock and prevent the timepiece mechanism from breaking. Inaddition, rust does not generate on it.

While the preferred embodiment of the invention, i.e., the watch casewith the case back by screws, has been illustrated and described, it isto be understood that the present invention is not limited to theprecise construction herein disclosed and can be applied to the othercases such as snap type or one-piece case and the same effect can beobtained.

As can be understood from the description above, the watch case,according to the invention, has both the merits of the metal case andthe plastic case. Therefore, the present invention will have variousgood effects on the design or the function of the watertight watch casesfor wrist watches.

What is claimed is:

1. A watertight watch case for a wrist watch comprising a ring-shapedinner metal case body having front and rear portions, said inner casebody having an outwardly facing shoulder thereon proximate said rearportion, an outer case body of plastic material surrounding said innercase body and resting against said shoulder, and means in engagementwith said inner case body for holding said outer case body against saidshoulder.

2. A watertight watch case as defined in claim 1, wherein said outercase-body is held to said inner casebody by a bezel engaging said innercase-body.

3. A watertight watch case as defined in claim 1, wherein said outercase-body is colored.

1. A watertight watch case for a wrist watch comprising a ringshapedinner metal case body having front and rear portions, said inner casebody having an outwardly facing shoulder thereon proximate said rearportion, an outer case body of plastic material surrounding said innercase body and resting against said shoulder, and means in engagementwith said inner case body for holding said outer case body against saidshoulder.
 2. A watertight watch case as defined in claim 1, wherein saidouter case-body is held to said inner case-body by a bezel engaging saidinner case-body.
 3. A watertight watch case as defined in claim 1,wherein said outer case-body is colored.